I can't speak for the east coast, but in Campbell River, I have walked up to the CG Cutter where it is normally moored at a regular town wharf. No extra security. They just tie it up. If it is ever decided to arm them, then the resultant security issues will be a serious hurdle to overcome. Guards would be required, duty watches etc, fencing, perhaps a secure "mini-base".
If we as trained and disciplined soldiers, sailors and airmen aren't to be trusted to hold magazines (for the younglings, in prehistoric times we kept our mags at home or in our ready lockers) what hope would the Coast Guard have of overcoming the firearms rules?
I don't see it happening without a huge culture shift and a very large infusion of cash!